This invention relates to pipe cutting tools, and more particularly, to pipe cutting tools for plastic pipes.
Homeowners have traditionally relied upon plumbers to repair and replace faulty plumbing. Professional plumbers are needed, in part, because older plumbing utilizing metal pipe, which require special equipment and experience to cut, repair and weld. The obvious difficulty in cutting metal pipe arises from the hardness of the steel or other metal used.
Although plastic pipe is now commonly used in new homes, plastic pipe can be difficult to cut to size because of its flexibility. For example, when attempting to cut plastic pipe with a hand saw to a desired length, application of sawing force to the pipe causes the pipe to bow, which results in an uneven cut. A pipe with an unevenly cut end may not be usable for attachment at the joint to which it is to be bonded.
While special tools have been developed to cut plastic pipe for use by plumbers and other skilled persons, some of such equipment is complicated to use, bulky or expensive, and thus not suitable for use by a homeowner or other unskilled person who may only need to cut a single length of plastic pipe. One special tool is described in U.S. Pat. No. 5,956,853 entitled PIPE CUTTING TOOL FOR PLASTIC PIPE, which issued Sep. 28, 1999, to the inventor hereof, and which is incorporated in its entirety herein. This patent describes a preferred embodiment of a pipe cutting tool which includes an annular collar in which a radial expansion slot for expansion of the collar and frictional engagement of the collar with the pipe to be cut. The preferred embodiment includes a cutting member having a blade mounted between opposing first and second blade holding members and a biasing spring attached to the first blade holding member, for pivotal attachment to the annular collar. In this arrangement the spring biasing member helps maintain contact of the cutting member with the plastic pipe to be cut. This configuration can, however, be complex to manufacture.
Thus, there remains a need for a plastic pipe cutting tool which is both inexpensive to manufacture and easy to use by an unskilled person. It is against this background that the significant improvements and advancements of the present invention have taken place.
It is the principal object of the present invention to develop a pipe cutting tool which may be easily operated by an unskilled person.
It is a further object of the present invention to develop a pipe cutting tool which will produce a clean and even cut fully transverse and perpendicular to the longitudinal axis of the pipe.
It is a yet further object of the present invention to develop a pipe cutting tool which can be economically made for use by homeowners or other unskilled persons, and which does not require the use of a vise, welding equipment or other tools or special knowledge to operate.
In accordance with the major aspects of the present invention, a tool for cutting an elongated plastic pipe is disclosed which includes (i) an annular collar having a fixed diameter, which is selectively positionable on the pipe for slideable movement along the length of the pipe to a predetermined position and separate selectable rotational movement about the predetermined position, (ii) a cutting member pivotably mounted to the annular collar, with the cutting member and annular collar rotated about the predetermined position, forming a circular score in the pipe until the pipe cutting through the initial score is complete, and (iii) an alignment ring also having a fixed diameter, which is selectively positioned to a predetermined position encircling the pipe and having means for releasable attachment to the pipe.
In a preferred embodiment of the present invention, the cutting member is pivotably mounted to the annual collar and includes a blade embedded in a molded blade holder. The biasing force needed to cut the pipe is preferably provided by pressure applied with the operator""s thumb to the cutting member. A biasing means such as a spring may also be used. In one preferred embodiment, the cutting member includes a widened portion which accommodates the operator""s thumb.
To use the pipe-cutting tool of the present invention, the alignment ring and annual collar are slid onto the pipe to predetermined positions side-by-side, with the leading edge of the annual collar adjacent the length of the pipe to be cut. The alignment ring is then releasably fixed into position. Thereafter, the annual collar is rotated about the pipe (or alternatively, the pipe rotated while holding the annual collar), while the annual collar is forced to maintain abutting contact with the alignment ring and a biasing force applied to the cutting member. Once the pipe is scored and cut, the alignment ring released from its fixed position on the pipe, and the alignment ring and annual collar are removed.
The aforementioned tool can be manufactured easily and economically, and thus may be made available to homeowners at an affordable price. When a homeowner or unskilled person utilizes the cutting tool of the present invention to cut a plastic pipe, a pipe end is produced which is even and fully transverse to the length of the pipe. The cleanly cut pipe end so produced is achieved without requiring the use of a vise, welding equipment or other tools or special knowledge.
A more complex appreciation of the present invention and its scope can be obtained from understanding the following detailed description of presently preferred embodiments of the invention, and the appended claims.